As a result of varying environments and missions aircraft have incurred crash landings with varying attitudes and velocities. Aircraft (e.g., rotorcraft) are designed to attenuate energy caused by impact when there are small lateral velocities. The ability for the airframe of the aircraft to attenuate energy decreases in conditions where there are skewed impact angles and substantial lateral velocities. Crashes have occurred with skewed impact angles and lateral velocities that exceed crash design specifications.
Airbags may be used to attenuate energy in the event of a crash or hard impact. For example, sensors may detect that a crash is occurring and deploy airbags internal to the aircraft. Airbags external to the aircraft may be deployed when a determination is made that impact is imminent and at a point before the impact occurs. To be effective, the external airbags need to be fully deployed before impact. Much like the airframe structure, the airbags are designed to attenuate energy resulting from level impacts with minimal lateral velocity.
Independent processing units and sensors are used to determine when a crash or impact is imminent, in order to engage airbags or other crash-related devices and systems. These processing units and sensors base their determinations or algorithms on various quantities, such as acceleration and velocity. The algorithms are susceptible to false triggers or false positives (e.g., declaring that a crash is imminent when in actuality it is not), such as when the aircraft is being flown over a building or going over an edge of a ship.